As others have mentioned, the snowball shows up on your HA if it gets deflected by a shield. So this happens when your random throw hits somebody with a shield and gets deflected. However...

There's a minor error in this text, where it's missing the username in "at __ but they reflected it!" I've just pushed a fix for this, but due to the randomness of it, it's difficult to test. So if anyone is able to confirm/deny this fix moving forward, please give me a ping to let me know :) Thanks!

Awesome, we'll consider this resolved then <3